1. Field of the Invention
The present invention relates to spine fixation components, constructs and assemblies and, more particularly, to mechanisms for retaining bone screws relative to a spinal implant once implanted.
2. Background Information
Spinal orthopedic assemblies and constructs such as spine plates, spinal bone screw assemblies for spinal rods and other devices have made a profound contribution to the correction of spinal deformities, accidents and other problems in the cervical as well as thoracic, lumbar and sacral spine. These and other spinal devices are typically fixed to vertebrae using vertebral bone screws. Vertebral bone screws are specially designed and manufactured bone screws that are placed into the bone of a vertebra. Vertebral bone screws placed in the vertebra offer superior strength and pull-out resistance as compared to other forms of fixation in spine surgery. The ability to achieve vertebral fixation has allowed surgeons to obtain more secure fixation of the spinal components involved, which permits more powerful correction of spine problems and reported better clinical outcomes.
Bone screws thus allow solid attachment of various types of spinal implants such as spine plates and spine rod holders to vertebrae of the spine. The spinal implants are thus configured to receive and retain one or more bone screws. Once implanted, it is important that a bone screw not back out. In this regard, various anti back out devices have been developed that attempt to limit and/or prevent bone screw back out. For example, anti back-out devices have been developed that attach into the drive socket of the bone screw and to the spinal implant. Those and other anti back out devices, however, suffer from deficiencies that make them less than ideal.
In view of the above, there is a need for an improved bone screw retention mechanism for spinal implants.